Device for generating an air system by means of an ejector

ABSTRACT

A device for generating an air stream through the venturi tube of an ejector, in which there are a number of channels for supplying air under pressure going through the wall of said venturi tube, and in which there is an inner tube slidably mounted in said venturi tube from a position where the orifices of said channels are substantially closed to a position where said channels are open.

iiite States Patent Tell 1MalCh 13, 1973 [54] DEVICE FOR GENERATING AN AIR [56] References Cited F N E T R SYSTEM BY MEANS O A El C 0 UNITED STATES PATENTS [75] Inventor: Peter Tell, 184 00 Akersberga,

Sweden 2,399,249 4/1946 Perignat ..417/183 3,175,515 3/1965 Cheely ..417/197 [73] Ass1gnee: Aktiebolaget Piab, Danderyd,

Sweden Primary Examiner-Carlton R. Croyle [22] Filed: April 13, 1971 Assistant Examiner-Michael Koczo, Jr.

NO: Attorney-Silverman & Cass [57] ABSTRACT [30] Foreign Application Priority Data A device for generating an air stream through the ven- May 14, 1970 Sweden ..66l5/7O turi tube of an j in which there are a number of 52 us. (:1. ..417/179 417/187 417 197 channels Supplymg Pressure ging 51 1111 C1 ..F( )4f 5/46 1 04f 5/48 through the wall 0f Said venturi and which [58] Field of Search 417/179, 197, 187,, 188, 183, there is an inner tube slidably mounted in said venturi 417/130 39 tube from a position where the orifices of said channels are substantially closed to a position where said channels are open.

7 Claims, 3 Drawing Figures PATENTEDHAR 1 3197s INVENTOR: PETER TELL ATTORNEY$ DEVICE FOR GENERATING AN AIR SYSTEM BY MEANS OF AN EJECTOR BACKGROUND OF THE INVENTION Until now, the required control of the air stream in ejector devices is generally brought about by a valve connected in an air pressure channel leading to the ejector at some distance from the ejector nozzle or the ejector nozzles within the venturi tube or by controlling the area of an annular ejector nozzle. In the latter case, the ejector nozzle is an annular air gap between a conical inner wall part of said venturi tube and one end of an inner tube which is displaceable inside the venturi tube and which can be brought nearer to or farther from said conical wall part.

In the first case a certain alteration of the channel area by means of the valve, does not bring about a corresponding alteration of the ejector efficiency in relation to the maximum efficiency of the ejector and, because of said lack of linearity, control of the ejector efficiency, by means of adjusting said valve, is difficult to make. In the second case the control of the efficiency is possible only within a limited range, because, when said annular air gap is very small, a turbulence will occur and said turbulence will influence the ejector efficiency in an uncontrollable way.

- The object of the present invention is to eliminate said drawback.

SUMMARY OF THE INVENTION The invention relates to a device for generating an air stream through a venturi tube by means of an ejector which is formed by a number of channels for air under pressure, the orifices of said channels being distributed along a circular line around the inner circumference of said venturi tube, in which the cross section areas of said channels can be varied by means of displacing an inner tube belonging to said venturi tube and which is concentric with the venturi tube and slidably fitted in the latter, wherein the inner wall surface of said venturi tube has a cylindrical part where said circular line is located and the end portion of said inner tube being tightly slidable on the inner wall surface of said cylindrical part and to be displaceable from a position, where the orifices of the channels are substantially open to a position where said orifices are substantially closed.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section through the device constructed according to the invention.

FIG. 2 is a similar axial section of the device constructed according to a more complete embodiment.

FIG. 3 is an axial section on a greater scale through the insertable sleeve of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The device according to the invention comprises three main parts viz. a venturi tube 1, an outer sleeve 2 and a displaceable, inner tube 3. The channel through the venturi tube 1 comprises a nozzle part 4 which is conical and the cross sectional area of which increases outwards. This nozzle part is a so called lava] nozzle. Said channel further comprises a cylindrical part 5, a

convex, rounded part 6 and a cylindrical part 7 and a threaded part 8. From the outer side of the venturi tube four channels 9 lead into that portion of the cylindrical part 7 which is adjacent to the rounded part 6. Said channels 9 are, as shown in FIG. I, inclined and are tangential or nearly tangential to the adjacent surface of the rounded portion 6.

The outer sleeve 2 is mounted on the venturi tube so as to be rotatable but not axially displaceable, 1 and to that effect two screws 10 reach with their ends into an annular groove 1 l on the outer side of the venturi tube. There are two annular packings 12 between the venturi tube 1 and the outer sleeve 2. Between said annular packings 12 there is an annular groove 13 in the sleeve 2, which together with the adjacent outer wall of the venturi tube forms an annular channel to which a preferably bendable inlet tube 14 is connected.

The adjustable, inner tube 3 has a portion 15 which is threaded into the portion 8 on the venturi tube 1. The end portion 16 of said adjustable tube 3 extends into the cylindrical part 7 of the venturi tube. An annular packing 17 is provided between the inner tube 3 and the inner wall of the venturitube. The inner wall of the end portion 16 is conical as shown, and because the inner tube is displaceable, said wall portion can be brought to cover and close the openings of the channels 9. A screw 18 inserted in a wall portion of the venturi tube 1 limits the movement of the adjustable, inner tube 3, so that it cannot be moved out from the venturi tube 1. To the outer (left hand) end of the inner tube 3, a flexible tube or the like is connectable. Such a tube can also be connected to the outer (right hand) end of the venturi tube 1.

When air under pressure is supplied through the conduit 14 said air will stream through the annular channel 13 and through the channels 9 into the venturi tube, and will sweep along the rounded passage portion 6. Thereby an ejector action is achieved in the channel through the inner tube 3 so that air will be streaming from said tube and through a hose or other conduit, which may be connected thereto from a container which may be connected to said hose or conduit. This air stream which is very powerful, because of the location of the place where air under pressure streams into the venturi tube and because of the coanda effect which is achieved along the inner wall of the venturi tube, is controllable by displacing the inner tube 3 in the venturi tube so that the inner end 16 of the inner tube more or less covers the openings of the channels 9. Because the left hand end of the inner tube 3 is generally connected to a flexible tube or the like, the venturi tube 1 should preferably be rotatable for achieving the axial displacement of the inner tube relative to the venturi tube. The rotation of the venturi tube is not prevented by the outer sleeve 2.

The powerful air stream which is obtained is capable of suctioning and transporting stuffs of different kinds or can be used for control of different processes.

The device according to the invention has especially that advantage that it is-composed of simple parts which are easy to manufacture. Further, the control of the air stream through the channel of the venturi tube takes place directly at the openings of the channels 9 by changing the areas of said openings, so that a change of said areas brings about a corresponding change of the action of the air under pressure and a corresponding change of the air stream through the device.

The device shown in FIG. 2 is essentially like the device shown in FIG. 1 and corresponding parts have corresponding reference numerals. However, in the device according to FIG. 2, there is an extra sleeve 21 inserted in the channel of the cylindrical venturi tube 1 and kept in place by means of an annular sealing member 22. The wall surface of the channel 23 through the extra sleeve 21 is shaped to form a streamlined transition zone between the sleeve and the rounded portion 6 of the venturi tube and also between the sleeve and the outlet part 4 of the venturi tube. Further, in the inner tube 3 there is inserted an extra tube 24 with an annular packing 25 and a channel 26. Said channel 26 has the same inner diameter as the minimum inner diameter of the extra sleeve 21. The extra tube 24 and the extra sleeve 21 provide thus a reduction of the opening in the inner tube 24 and the venturi tube 1 without decreasing the outstreaming of air from the channels 9. Therefore, by means of said extra sleeve and said extra tube, a still more powerful airstream will be obtained through the device. The outstreaming of air under pressure through the openings of the channels 9 is still controllable by axial displacement of the inner tube in the venturi tube as described in connection with FIG. 1.

The extra sleeve 21 and the extra tube 24 are easily exchangeable for other such extra devices with smaller diameter or bigger diameter. In FIG. 3, there is illustrated an extra sleeve 21 the minimum inner diameter of which has the greatest possible value with respect to the outer diameter of the sleeve.

The invention is not limited to the embodiments illustrated in the drawing because the invention may be modified in several ways within the scope of the appended claims. Thus, for example, the number of the channels 9 and their inclination in the venturi tube may be varied. Further, different means for the mutual displacement of the inner tube and the venturi tube may be provided. Still further, the annular groove forming the annular channel 13 may be provided in the outer wall of the venturi tube instead of the inner wall of the outer sleeve 2.

What we claim is:

1. A device for generating an air stream comprising, a venturi tube with an ejector formed therein, the ejector including a plurality of channels adapted to receive a pressurized air stream, each of said channels being inclined relative to the longitudinal direction of the venturi tube and having a respective orifice opening positioned along a circular line around the inner circumference of the venturi tube upon a cylindrical part thereof, an inner tube having an end portion engaged within the cylindrical part, the inner tube being displaceable from a position in the cylindrical part where the orifices are substantially open to a position where the orifices are substantially closed such that the exit cross sectional areas of the channels may be varied according to displacement of the inner tube.

2. A device as claimed in claim 1 in which said inner tube is threadedly engaged within the venturi tube upstream of said cylindrical part, and the axial displacement of the inner tube in the venturi tube is limited by a StOg) screw threadedjn the wall of said ven turi tube.

. A device as claimed in claim 1 in WhlCh there IS an annular bead positioned on the venturi tube immediately upstream of the orifices, and the channels are tangential with the surface of the annular bead.

4. A device as claimed in claim 1 in which an outer sleeve is tightly mounted outside said venturi tube and an annular groove is formed between the outer sleeve and the outer wall surface of said venturi tube, the orifice openings of said channels being located in said annular groove.

5. A device as claimed in claim 4 in which said outer sleeve is rotatably mounted on said venturi tube but prevented from being axially displaced by means of one or more pins or screws in one of said tube or sleeve which cooperate with one or more annular grooves in the other of said tube or sleeve.

6. A device as claimed in claim 1 in which the venturi tube includes a cylindrical inner part and an extra exchangeable sleeve is provided for insertion therein, an extra exchangeable tube being provided for insertion in said inner tube, the smallest inner diameters of said extra sleeve and said extra tube being substantially the same, whereby positioning of said extra sleeve and extra tube will reduce the inner area of said venturi tube and said inner tube.

7. A device as claimed in claim 6 in which there is a streamlined transition zone between said extra sleeve and the adjacent inner wall surfaces of said venturi tube at each side of said extra sleeve. 

1. A device for generating an air stream comprising, a venturi tube with an ejector formed therein, the ejector including a plurality of channels adapted to receive a pressurized air stream, each of said channels being inclined relative to the longitudinal direction of the venturi tube and having a respective orifice opening positioned along a circular line around the inner circumference of the venturi tube upon a cylindrical part thereof, an inner tube having an end portion engaged within the cylindrical part, the inner tube being displaceable from a position in the cylindrical part where the orifices are substantially open to a position where the orifices are substantially closed such that the exit cross sectional areas of the channels may be varied according to displacement of the inner tube.
 1. A device for generating an air stream comprising, a venturi tube with an ejector formed therein, the ejector including a plurality of channels adapted to receive a pressurized air stream, each of said channels being inclined relative to the longitudinal direction of the venturi tube and having a respective orifice opening positioned along a circular line around the inner circumference of the venturi tube upon a cylindrical part thereof, an inner tube having an end portion engaged within the cylindrical part, the inner tube being displaceable from a position in the cylindrical part where the orifices are substantially open to a position where the orifices are substantially closed such that the exit cross sectional areas of the channels may be varied according to displacement of the inner tube.
 2. A device as claimed in claim 1 in which said inner tube is threadedly engaged within the venturi tube upstream of said cylindrical part, and the axial displacement of the inner tube in the venturi tube is limited by a stop screw threaded in the wall of said venturi tube.
 3. A device as claimed in claim 1 in which there is an annular bead positioned on the venturi tube immediately upstream of the orifices, and the channels are tangential with the surface of the annular bead.
 4. A device as claimed in claim 1 in which an outer sleeve is tightly mounted outside said venturi tube and an annular groove is formed between the outer sleeve and the outer wall surface of said venturi tube, the orifice openings of said channels being located in said annular groove.
 5. A device as claimed in claim 4 in which said outer sleeve is rotatably mounted on said venturi tube but prevented from being axially displaced by means of one or more pins or screws in one of said tube or sleeve which cooperate with one or more annular grooves in the other of said tube or sleeve.
 6. A device as claimed in claim 1 in which the venturi tube includes a cylindrical inner part and an extra exchangeable sleeve is provided for insertion therein, an extra exchangeable tube being provided for insertion in said inner tube, the smallest inner diameters of said extra sleeve and said extra tube being substantially the same, whereby positioning of said extra sleeve and extra tube will reduce the inner area of said venturi tube and said inner tube. 